In this paper the Accident Source Term Evaluation Code (ASTEC) is validated against the blowdown experiments Marviken M19 and M24. These tests mainly differed by the mass flow of the released steam from the pressure vessel and the configuration of the vent pipes in the pressure suppression chamber — while in M19 all vent pipes were arranged to one pool, in M24 they were split up by 27 pipes in one and one pipe in another pool.

For the simulation of both tests, an existing model of the facility for another lumped parameter code COCOSYS was transferred to ASTEC. In this data set a simple zone and a flow connection was used to model the pressure suppression chamber. Further simulations were performed with another approach for the pressure suppression chamber, so called “DRASYS”-zones. Using the DRASYS model, the user has to specify more inputs for the geometry of the pressure suppression chamber. The results of the simulations are in good agreement to the measured pressure and temperature of both tests. By using the DRASYS model in ASTEC, the results were improved slightly for M19 compared to the simple pressure suppression zone model. In opposite, the results of the simple model are in better agreement to M24. Overall the conclusion is that ASTEC is able to simulate a Blow Down in plant scale with both models.

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